http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48049
Summary: 4.6 Regression? DW_AT_accessibility change breaks GDB
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: debug
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: jan.kratoch...@redhat.com
CC: ja...@gcc.gnu.org
Target: x86_64-fedora15-linux-gnu
Only -gdwarf-3 is affected here:
debug/45124 has changed DW_AT_accessibility generation for DWARF-3+.
GGC-4.5 was compatible with GDB but both were not compliant with DWARF-3+.
GCC-4.6 is now DWARF-3+ compliant but it breaks GDB.
By providing DW_AT_accessibility explicitly even for cases when one could
assume a default value may be both compatible with existing GDBs and DWARF-3+
compliant.
I believe this was the Jakub's intention but it did not get implemented in GCC
that way:
Bug 45124 Comment 1:
> I'm afraid we need to live with some extra DW_AT_accessibility attributes for
> > compatibility.
class C { private: int private_; } v;
gcc -c -Wall -gdwarf-3
GNU gdb (GDB) 7.2.50.20110309-cvs
PASS: g++ (GCC) 4.5.3 20110124 (prerelease)
(gdb) ptype C
type = class C {
int private_;
}
<2><37>: Abbrev Number: 3 (DW_TAG_member)
<38> DW_AT_name : (indirect string, offset: 0x2e): private_
<3c> DW_AT_decl_file : 1
<3d> DW_AT_decl_line : 4
<3e> DW_AT_type : <0x45>
<42> DW_AT_data_member_location: 0
<43> DW_AT_accessibility: 3 (private)
but:
FAIL: g++ (GCC) 4.6.0 20110309 (experimental)
(gdb) ptype C
type = class C {
public:
^^^^^^^
int private_;
}
because:
<2><37>: Abbrev Number: 3 (DW_TAG_member)
<38> DW_AT_name : (indirect string, offset: 0x54): private_
<3c> DW_AT_decl_file : 1
<3d> DW_AT_decl_line : 4
<3e> DW_AT_type : <0x44>
<42> DW_AT_data_member_location: 0
(That GDB should be changed is sure but there may be some DW_AT_producer
checks, depending on how it gets resolved for GCC-4.6.0.)
